One type of metallurgical vessel known as the argon-oxygen or AOD converter consists of a pivotable, generally pear-shaped vessel having an upper opening. A plurality of tuyeres, generally two or three in number, extend radially through the side wall of the vessel and they are spaced 40.degree. to 60.degree. apart, usually in a horizontal position, 17 to 25 centimeters above the flat vessel bottom. This places the inner ends of the tuyeres below bath depth which is typically one meter.
In a typical conversion process, the AOD vessel is charged with electric furnace hot metal containing between 0.8 and 1.5% carbon. A mixture of oxygen and argon having a ratio of about 3 parts oxygen to 1 part argon is blown through the center tuyere while argon or air is delivered through the outer tuyere pipe as a coolant or shielding fluid. During the process cycle, the ratio of argon and oxygen delivered to the center tuyere pipe is reversed in programmed steps.
Argon-oxygen vessels are commonly supported on a trunnion ring having radially extending trunnion pins supported on bearings. One trunnion pin is also coupled to a drive mechanism whereby the vessel may be tilted for pouring, deslagging and sampling.
The argon-oxygen process suffers a disadvantage of relatively high cost as a result of refractory and equipment wear and high argon consumption. For example, the refractory surrounding the tuyeres in AOD vessels erodes relatively rapidly despite the use of expensive argon as a cooling fluid. Also, as a result of the blowing pattern, AOD vessels have a tendency to oscillate causing wear in the support bearings and drive assembly.